1. Field of the Invention
This invention relates to electrical connectors and, more particularly, to bi-level card edge connectors and a method of manufacturing the same.
2. Prior Art
In electrical arts it is a common practice to use a connector to mechanically and electrically couple a mother printed circuit board with a daughter printed circuit board as of the vertical edge card variety. In such a practice, there has been an evolution towards placing electrical contacts closer and closer together while maintaining a high, constant stress between the electrical contacts and the areas to be contacted. In placing the contacts closer together, as to 20 contacts per linear inch, the width of each contact must decrease. One such connector is found in U.S. Pat. No. 4,846,734, entitled "Vertical Edge Card Connectors" by Thomas G. Lytle which is assigned to the same assigned as herein and is incorporated by reference in its entirety herein.
There has also been developed a special type of connector which is known in the art as a bi-level connector; i.e.: a connector having two types of contacts that make contact with a daughter printed circuit board in two locations or at two levels. The two types of contacts are generally intermixed or alternatingly arranged in two opposing rows. The first type of contacts are arranged at a predetermined pitch, such as 100 mils, between the first type of contacts. The second type of contacts are also arranged at a predetermined pitch, such as 100 mils, between the second type of contacts such that there is a 50 mils pitch between the adjacent first and second contacts. One such connector is described in copending patent application Ser. No. 07/287,765, filed Dec. 21, 1988, now U.S. Pat. No. 4,934,961, entitled "Bi-Level Card Edge Connector And Method of Making The Same" by Piorunneck et al. which is assigned to the same assignee as herein and which is incorporated by reference in its entirety hereby.
U.S. Pat. No. 4,045,114 to Dechelette discloses a two part housing for an electrical connector that are bonded together to secure the contacts in their required positions. U.S. Pat. No. 4,842,538 to Noschese disclosed a card edge connector having a body shell and follower with bi-level contacts therebetween. U.S. Pat. No. 4,179,177 to Lapraik discloses a card edge connector with an outer housing and inner housing. U.S. Pat. No. 4,298,237 to Griffith et al. discloses a card edge connector having contacts at three levels aligned in columns.
However, even thought the art is replete with many different types of connectors, a problem still exists with providing a card edge connector with contact spacing at a sufficiently close and dense an arrangement to allow for faster communication between mother and daughter printed circuit boards such as with the use of more numerous contacts and yet still be suitably sized for practical applications such as in relatively small desktop computers. One problem in this regard is that prior art connectors have been only 8, 16 and 32 bit connectors. Whereas higher bit connectors, such as 128 or 256 bit or higher, could obviously transmit signals at a higher rate of speed than old connectors. However, one major problem with connectors having closely spaced contacts is the problem of cross-talk and induction between the contacts due to electromagnetic forces. A further problem exists in that faster signals have larger electrical spikes which produce stronger electromagnetic impulses. In addition, another problem with connectors is that the contacts must provide a relatively short or direct path between the daughter board and mother board to prevent propagation delays and, the signal sent through the contacts must be impedance matched to prevent reflection waves.
It is therefore an objective of the present invention to provide a new and improved connector and method of manufacturing the same that can overcome the above problems in the prior art as well as provide additional features and advantages.